Role Provisioning not working for employee without Managers

Summary

Role Provisioning not working for employee without Line Managers

Content

I have simple Role Provisioning,

All employees in A BU should get Employee and XX BU Role,
                           B BU should get Employee and XX BU Role.

It's working fine but its not attaching the role to the employee's who don't have a Line Manager and i don't have any other conditions. Is it expected behaviour that Role provisioning will not work if there is no line manager attached to the employee?

Thanks
Jag